The present invention relates to a determination of a physical state of an optical device by measuring a response signal.
Optical devices showing response characteristics dependent on a physical state, e.g. the temperature, pressure, strain or mechanical force are widely used within optical systems. Often, such characteristics variations are unwanted and thus measurements are taken to reduce the effects of the variations or to measure such variations.
Optical devices with wavelength dependent characteristics, especially Fiber Bragg Gratings (FBG), Fabry Perot Filters or Etalons, are employed in a variety of engineering and environmental sensing applications. The wavelength response characteristics of those devices depend on their physical states caused by environmental conditions at those devices. Changes of the physical state can therefore be determined by analyzing a returned signal.
U.S. Pat. No. 6,449,047 discloses a tunable laser with an accurately calibrated wavelength output which can be rapidly scanned or swept over a selected wavelength band. Such lasers may generate wavelengths in the 1550 nm range and can be swept over about 50 nm. These lasers are used as components of sensor interrogator systems, which determine the power of reflected or transmitted by Fiber Bragg Gratings (FBG) depending on the wavelength of an incident beam.